Benign vs. Malignant Skin Adnexal Neoplasms: How Useful are Silhouettes?

Abstract

Background:

Skin adnexal tumors are daunting diagnostic problems. Cytologic atypia does not always imply malignancy and “typia” does not underscore a benign course. Bernard Ackerman first described criteria on silhouettes that enable distinction between the two.

Aims:

To evaluate the histologic features on silhouettes of benign and malignant skin adnexal tumors. To identify overlaps and confounding features.

Materials and Methods:

A blinded retrospective review of all skin adnexal neoplasms between 1995 and 2007 was done, with a total of 68 cases. We studied 16 histologic parameters on scanner view and categorized them as benign or malignant. They were compared with the final histologic diagnosis. Statistical analysis was performed using chi-square test.

Results:

15 criteria attained statistical significance. Features that proved highly sensitive and specific were: Circumscription, ulceration, uniform size of cell aggregates, discrete arrangement, preserved adnexae and necrosis. Criteria that were sensitive but not very specific include: Symmetry, V-shape, vertical orientation, smooth margins, compressed fibrous tissue, type of clefting, shelling out and geometric shapes. Presence of epithelial cells in singles was not helpful.

Conclusion:

Malignant skin adnexal tumors are differentiated accurately from benign ones by their contrasting silhouettes. Pathologists should heed the impression formed on scanner view, before evaluating cytologic features.